abdomen were fatal, whereas today with our knowledge of methods of infection and the use of antiseptics, cases have recovered with as many as nineteen wounds in the abdominal viscera. Wounds in the joints were in earlier times considered as mortal, and even under the best conditions five or six months were required for them to heal.

Up to a century ago hospitals could be recognized at long distances by their stench. They were pest holes of infection and were much more dangerous for the wounded patient than isolated private homes. When the nature of infection and disease was not known the germs were allowed to remain on surgical instruments, cots, and clothing from one patient to infect the next and thus disease and death were passed on in an endless chain.

Precautions were taken by physicians, but they were precautions that amounted to nothing and the real vital methods of control were not used since everyone was ignorant of the nature of disease.

Let us now see what brought about the change from the old to the new, from the high mortality to the low.

Back in the last quarter of the seventeenth century a Dutch linen-draper, Anton von Leewenhock, spent his leisure time grinding lenses. His lenses were better than those made by anyone else, and he used them to magnify various substances such as drops of water, saliva, and putrifying matter. To his great delight he found these things filled with living moving things which he called animals. Thus for the first time in the history of the world bacteria were seen by mortal eye.

For a long time the idea of spontaneous generation was held. Von Helmont in the 16th century wrote that mice can be spontaneously generated by merely placing some dirty rags in a receptacle together with a few grains of wheat and a piece of cheese. He also said, "Scoop out a hole in a brick, put into it some sweet basil, lay a second brick upon the first so that the hole may be imperfectly

covered. Expose the two bricks to the sun and at the end of a few days the smell of sweet basil, acting as a ferment, will change the herb into a real scorpion."

With such ideas believed everywhere, the finding of microbes awakened no great interest outside of a few who were naturally curious at everything strange and new. It was believed that the new organisms sprang into being spontaneously and, therefore, the fact that they were found almost everywhere was thought to have no importance whatever. This idea continued till the middle of the last century when the idea of spontaneous generation met its final defeat after a hard fought combat on the part of its supporters.

In 1857 a young French scientist, Louis Pasteur, sent a paper on "Lactic Acid Fermentation" to the Lille Scientific Society and in December of the same year he presented to the Paris Academy of Sciences a paper on "Alcoholic Fermentation" in which he concluded that "the deduplication of sugar into alcohol and carbonic acid is correlative to a phenomenon of life." A new era in medicine dates from these two papers. They laid the foundation to a true knowledge of the nature of fermentation and disease, and to the fact that life can come only from life. Living creatures, whether large or small, do not come suddenly into being without having other living creatures from which they come.

At the middle of the last century we did not know much more about the actual causes of the great scourges of the race-the plagues, the fevers, and the pestilences -than did the Greeks and Romans. Here comes Pasteur's great contribution. Before him, Egyptian darkness; after his work, a light that increases in brightness with the years. The fact that fevers were catching, and that epidemics spread, was ancient knowledge, but it was not until the studies of Pasteur on fermentation that any sure ground on which to stand was found.

As his studies in fermentation progressed he doubtless caught the analogy between disease and fermentation; and then came the suggestion: "What would be most desirable is to push those studies far enough to prepare the road for a serious research into the origin of various diseases." If the changes in lactic, alcoholic, and butyric fermentations are due to minute living organisms, why should not the same tiny creatures make the changes that occur in the body in the putrid and suppurative diseases? Pasteur was not the first to suggest that disease might be caused by living organisms; but he was the first who had the training and technique to demonstrate the truth of the theory.

Connecting up closely with the fundamental researches of Pasteur came the investigations of a German scientist Robert Koch, who demonstrated the constant presence of germs in the blood of animals dying from disease. Years before, those organisms had been seen by Pollender and Davaine, but the epoch-making advance of Koch was to grow the organisms in a pure culture outside the body, and to produce the disease artificially by inoculating animals with the cultures.

The practical application of the researches of Pasteur to surgery was first made by a young surgeon in Glasgow by the name of Joseph Lister. In the following words he outlines the way in which the application was made:

"Turning now to the question how the atmosphere produces decomposition of organic substances, we find that a flood of light has been thrown upon this most important subject by the philosophic researches of M. Pasteur, who has demonstrated by thoroughly convincing evidence that it is not to its oxygen or to any of its gaseous constituents that the air owes this property, but to minute particles suspended in it which are the germs of various low forms of life, long since revealed by the microscope, and regarded as merely accidental concomi

tants of putresence, but now shown by Pasteur to be its essential cause, resolving the complex organic compounds into substances of simpler chemical constitution, just as the yeast plant converts sugar into alcohol and carbonic acid."

From these beginnings modern surgery took its rise. The whole subject of the elimination of the terrors of wound infection forms one of the most brilliant chapters in the history of medicine. Physicians working throughout the ages were able to cope with infection and disease but imperfectly. It was only when trained research workers devoted themselves to a study of the fundamental causes of disease that real significant progress was made; more was then accomplished in a half century than in all of the past history of the world.

CHAPTER III

THE CONQUEST OF YELLOW FEVER

One of the most romantic chapters in the history of scientific research is that connected with the conquest of yellow fever-that terrible scourge of tropical countries which for centuries held dominion, and against which man seemed powerless to fight. Millions of lives were sacrificed, and the almost undisputed sway of the disease made it very difficult for people from temperate climates to live with any degree of safety in tropical regions.

Ever since the discovery of America the disease has been one of our greatest scourges, permanently epidemic in the Spanish Main, often extending to the Southern States, occasionally into the north, and frequently it has crossed the Atlantic where it became epidemic on the west coast of Africa. The records of the British Army in the West Indies show an appalling death rate chiefly from this disease. At Jamaica, for the 20 years ending in 1936, the average mortality was 101 per thousand, and in certain instances as high as 178. In the Southern States there were frequent epidemics of yellow fever which caused the most profound consternation. In an epidemic which occurred in Philadelphia in 1793, ten thousand people died in three months, but in these northern latitudes the epidemic ceased with the coming of cold weather when the breeding places of mosquitoes became frozen. Havana for generations had been a hotbed of yellow fever and there seemed to be no relief even though some of the best minds of the medical profession gave it their most serious consideration.